In an interview with The Sun, director Rob Marshall hinted they are already in the early stages on a second sequel to Mary Poppins:
“It is early stages but I will say right now that there were eight books, so there’s a lot of great material still to mine. That’s what we worked from, those incredible eight books of P.L. Travers. So, you know…”
With a domestic total of over $142 million (at time of posting) and generally positive reviews, a sequel to Mary Poppins Returns is inevitable, as would be the return of Emily Blunt in the titular role. Unless, of course, they wait another five decades to make it, which is unlikely. We’re just waiting for the remake of the Gnome Mobile.